The present invention relates generally to cooling systems for aircraft and for aircraft jet engines, and more particularly to a new integral cooling system for a jet engine integral starter/generator.
With the advent of more- and all-electric aircraft, the number and size of aircraft hydraulic systems are being reduced. One result of this process is that the aircraft starter/generator system is being incorporated inside the jet engine. Because this is a high temperature and high heat flux region, efficient dissipation of heat, or cooling, of the starter/generator is critical. Permanent magnet and switched reluctance starter/generator configurations require operating temperatures to be maintained below the Curie point of the magnets and soft magnetic materials.
The prior art has experimented with a variety of apparatus and systems for cooling turbine, or jet, engine parts. One such apparatus is a rotating two-phase thermosyphon, or wickless heat pipe. A heat pipe uses successive evaporation and condensation of a working fluid to transport thermal energy, or heat, from a heat source to a heat sink. A rotating thermosyphon uses centrifugal forces to return condensed working fluid, or condensate, from a condenser (where transported thermal energy is transferred to the heat sink by condensation) to an evaporator (where the thermal energy to be transported is absorbed from the heat sink by vaporization). Thermosyphons, like other heat pipes, can transport very large amounts of heat in the vaporized working fluid.
Unfortunately, because the cooling requirements for a jet engine integral starter/generator are so great, prior art thermosyphons and thermosyphon systems will be unable to provide the amount of cooling needed for a jet engine integral starter/generator.
Another problem with prior art thermosyphons and thermosyphon systems, particularly off-axis systems, is that they can cause imbalance problems, particularly during startup of rotation. The radius of rotation and angular velocity of integral starter/generators, combined with the movement of the aircraft itself, can cause "g" forces significantly greater than experienced by the aircraft itself, making imbalance problems even more critical.
Thus it is seen that there is a need for new rotating thermosyphons and thermosyphon systems that, while exploiting the advantages of existing thermosyphons, will provide the additional cooling needed for jet engine integral starter/generators and other like apparatus in very high temperature and heat flux environments.
It is also seen that there is a need for new rotating thermosyphons and thermosyphon systems that are inherently balanced, especially during startup.
It is, therefore, a principal object of the present invention to provide a new rotating thermosyphon and thermosyphon system particularly adapted for cooling jet engine integral starter/generators and the like.
It is another object of the present invention to provide a new rotating thermosyphon and thermosyphon system that is inherently balanced, particularly during startup.
It is a feature of the present invention that it eliminates the external coolant loops and pumps required for other cooling systems.
It is another feature of the present invention that its use of multiple thermosyphon cells will provide redundant cooling capabilities and increased reliability should one of the thermosyphon cells fail.
It is an advantage of the present invention that it is inherently reliable and will require little maintenance.
It is another advantage of the present invention that it will eliminate the startup imbalance problems of prior art off-axis thermosyphon systems.
These and other objects, features and advantages of the present invention will become apparent as the description of certain representative embodiments proceeds.